The present invention relates to a trussed girder, a roof framing using the trussed girder and a method of constructing the roof framing of a building using the trussed girder.
For long span roof framings, there are conventionally used various structures such as a trussed structure, shell structure, suspended structure and pneumatic structure. Among these structures, the trussed roof framing structure using parallel long span trussed girders are widely used since it does not increase ceiling space not used and provides ease in expansion of the building.
However, such long span trussed girders as well as long span trussed girders for other use have drawbacks in that when the span is extra large, deflection thereof becomes considerably large and the trussed girder take larger part of the total weight of the building, so that cost performance is reduced.
Further, in construction of such a long spanned trussed roof framing, according to the prior art, structural elements forming outer walls of the building are erected, and then a roof framing which is prefabricated on the ground is craned and bridged between the structural elements.
However, such a long spanned trussed roof framing is disadvantageous in that it necessitates an extra large crane for lifting the roof framing, and in that indoor temporary works for the construction of the roof are rather laborious. These result in increases in construction term and cost.